As is well known in the art, many radiotherapy and radiosurgery systems employ radiation sources for producing radiation beams, and radiation modulators (e.g., collimators, attenuating blocks and physical compensators) for defining radiation beam characteristics such as beam shape and/or beam intensity profiles. Such beams are used for imaging or treatment. Radiation modulators are either rigidly integrated with the radiation source housing or are detachable units capable of being on-demand attached to the radiation source housing.
When in use, a detachable beam modulator and a radiation source housing are rigidly attached to each other, such that not a single degree of freedom is available for a relative displacement between the two. Albeit leaves of a multi-leaves collimator are adapted to move, a detachable multi-leaves collimator system is also rigidly attached to the radiation source housing.
As is also well known in the art, radiation-imaging systems are used for target localization. For example, kilovolt x-ray systems incorporate x-ray sources and associated detectors, and portal imaging systems use megavolt radiation sources for treatment and imaging. Such imaging systems are either integrated with the radiation source housing or are separate stationary units, generally ceiling and floor mounted dual units, since target localization requires imaging from two orientations. Once target position is determined, a sophisticated treatment couch (incorporating up to six motion-related degrees of freedom) moves the patient to the desired position.
Industry leaders currently offer systems where a radiation source, a multileaf collimator and imaging devices are integrated into one unit, operating in conjunction with a sophisticated treatment couch. Such units may be used for Image-Guided Radiation Therapy (IGRT) for the purpose of improved treatment due to improved target localization in real-time. For example, Siemens Medical Solutions manufactures the PRIMATOM System. This is a multifunctional hybrid configuration, consisting of a Siemens PRIMUS Linear Accelerator and a Siemens SOMATOM CT scanner with Sliding Gantry. The PRIMATOM System is intended to combine image guidance with radiation treatment delivery, with the aim of providing accurate, near real-time target localization within the treatment room. The oncologist is provided with current information on the size, shape and location of the target volume and nearby critical organs. Since the patient is in a ready-for-treatment position during CT acquisition, the information can be applied immediately for improved treatment accuracy.
IGRT may provide fast, 3-D tumor localization prior to irradiation, thereby providing the ability to accurately deliver escalated doses, reduce complications, and evaluate therapeutic effectiveness of treatment. X-ray or ultrasonic diagnostic imaging in the treatment room may provide diagnostic quality images with the patient in the actual treatment position, and may help indicate anatomical movement of the patient during treatment.
However, the prior art systems with integrated radiation source, collimators and imaging devices, in conjunction with a sophisticated treatment couch, are expensive, cumbersome and not easily adapted to units already in use.